Turbochargers for internal combustion engines are conventionally used in order to reduce the fuel consumption and to increase the output of the internal combustion engine.
Since internal combustion engines are subject to widely varying operational states, such as different rotational speeds and load conditions, the turbocharger also experiences differing conditions such as the exhaust flow rate, operational temperatures, and the like. Furthermore, intake requirements of pressurized intake air discharged from the compressor of the turbocharger differ in response to the variation of the operational conditions of the internal combustion engine. At some extremes of these conditions the operational efficiency of the turbocharger is substantially reduced, such as in the choke or surge conditions
Therefore, turbochargers have been developed which enable an adaptation to current operational conditions on the turbine side of the turbocharger. The adaptation to operational conditions on the turbine side includes, for example, the variation of the geometry of turbine inflow passages.
The U.S. Pat. No. 4,643,640 proposes a nozzle for passing a fluid such as exhaust gas, comprising a plurality of vanes for directing the flow by exerting a swirl effect to the fluid, and for adjusting the passage area of the nozzle. In such a structure according to the prior art, the vanes are supported rotatably in the passage. By appropriate rotating of the vanes, the swirl effect and/or the passage area can be set in accordance with the operational requirements.
In most variable nozzle turbines, vanes are usually made by either MIM (metal injection molding) or casting processes. U.S. Publication No. 2007/0041832 A1 proposes a rotatably supported vane comprising a sheet metal contour attached to an outer circumference of a portion of a shaft.
There continues to be a need for inexpensive and effective turbocharger components that provide for efficient operation and limit wear while minimizing construction costs. Preferred embodiments of the present invention satisfy these and other needs, and provide further related advantages.